Blood filter



FIG. 1 is a front perspective view of a blood filter showing my newdesign;

FIG. 2 is a left side elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof.

The ornamental design for a blood filter, substantially as shown anddescribed.